Children with asthma are thought to have impaired sleep quality and quantity. In this study, we investigated which of the many sleep aspects are associated with asthma. Our sample consisted of 2529 children (aged 11 years) who participated in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study. Parents reported about asthma symptoms (wheezing, dyspnoea, prescription of inhaled corticosteroids and asthma diagnosis) and children reported about different aspects of sleep (bedtime, rise time, sleep quality and daytime sleepiness/tiredness). Results were analysed with (logistic) regression analysis. Children with frequent asthma symptoms significantly more often reported that they felt sleepy or tired during the day (34.4% experienced daytime sleepiness/tiredness at least once a week) than children without asthma symptoms (22.2%) and children with infrequent asthma symptoms (21.9%). This association was not confounded by sex, age of the child, parental educational level or smoking inside the house; the effect was also not modified by sex. There were no associations between asthma and bedtime, time spent in bed or sleep quality. Children with frequent asthma symptoms experienced daytime sleepiness/tiredness more often than children with infrequent or no asthma symptoms. Otherwise, children with asthma did not differ much from children without asthma with regard to sleep.